Sudoku

Sudoku is the classic free online number puzzle, playable in your browser with no download and no sign-up. Fill the 9×9 grid so every row, column, and 3×3 box contains the digits 1 to 9 exactly once. Choose Easy, Medium, or Hard, use pencil-mark notes to plan, and race your own best time on phone or desktop.

How to play

• Pick a difficulty: Easy, Medium, or Hard.
• Tap a cell, then tap a number from 1 to 9 to place it.
• Each row, column, and 3×3 box must hold every digit 1–9 with no repeats.
• Turn on Notes to add small pencil marks for candidate numbers.
• On a keyboard, arrow keys move, 1–9 fill, Backspace erases, and N toggles notes.
• Fill the whole grid correctly to solve the puzzle and stop the timer.

Start with the rows, columns, and boxes that are already most filled — they leave the fewest options and give you free placements. When you are stuck, pencil in every candidate for a cell, then look for a digit that can go in only one spot within a row, column, or box. The grid highlights conflicts and matching numbers, so lean on those cues instead of guessing.